(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[5.00]
PW[Diamond]PB[Katscher]EV[BGC 1976]RO[6]PC[Cambridge]US[GoGoD95]C[Comments by Jon Diamond, 5 dan]RE[W+2.00]
;B[pd]
;W[cq]
;B[dd]
;W[qp]
;B[op]
;W[dj]
;B[qq]
;W[lq]
;B[rp]
;W[ip]
;B[cg]C[This could be played at 99 or 26.]
;W[qf]C[Wariuchi at 13 is better. The 12 and 37 become miai. The sequence up to 25 leaves black with a better position. ]
;B[qi]
;W[qc]
;B[qd]
;W[pc]
;B[od]
;W[rd]
;B[re]
;W[rc]
;B[qe]
;W[nc]
;B[nd]
;W[mc]
;B[le]
;W[qo]C[This move is rather poor - white only creates a heavy, weak group. A play directly at 30 would be more appropriate.]
;B[ro]
;W[qn]
;B[pq]
;W[pj]
;B[pl]C[Better at 32.]
;W[qj]
;B[rl]
;W[ri]
;B[nk]
;W[rk]C[White has given up three stones in exchange for the security of the group including 30. The overall result is better for white, although black now has sente.]
;B[ql]
;W[ph]
;B[cl]
;W[fc]
;B[dc]
;W[md]
;B[me]
;W[of]
;B[nf]
;W[kd]
;B[ni]
;W[sl]C[With this move white is certain of life.]
;B[sm]
;W[sk]
;B[rn]
;W[ci]
;B[ef]C[Although large in relation to the corner and the upper side, this move is not urgent. Black should have played at 54 to leave white with a weak group.]
;W[el]
;B[em]
;W[fm]
;B[en]
;W[dl]
;B[cm]
;W[co]
;B[cn]
;W[ep]
;B[bo]
;W[bp]
;B[do]
;W[cp]
;B[fp]
;W[fo]
;B[fn]
;W[go]
;B[gm]
;W[fl]
;B[gn]
;W[ck]C[54-74: In attacking black's group, white formed territory on the lower side and secured eye-shape for the left side group. Moreover, he still has some aggressive potential.]
;B[ho]
;W[gp]
;B[in]
;W[jp]
;B[ko]
;W[mo]C[This was the sealed move, Played quickly, it is an obvious mistake since white cannot afford to answer 85 at 87. White 80 at 87 would have been about 10 points better. ]
;B[hp]
;W[hq]
;B[iq]
;W[gq]
;B[lp]
;W[kq]
;B[mp]
;W[hk]C[White thought that he was losing and played 88 to reduce black's centre, but 89 was very severe. If white had played 88 at 90, then he would still have been ahead.]
;B[ic]
;W[hd]
;B[oc]
;W[ob]
;B[id]
;W[ie]
;B[he]C[Fatal mistake. After this white can play 96, force black to escape, and then capture 95 to gain easy life to the left. 95 should be at 97, and then black can either escape without giving white eyes, or, should white block the exit to the centre, connect underneath 40. ]
;W[hc]
;B[je]
;W[if]
;B[jd]
;W[gf]
;B[fd]
;W[gd]
;B[hb]
;W[fe]
;B[jf]
;W[ig]
;B[jk]
;W[eb]
;B[db]
;W[bg]C[Poor yose. This should be at 114 to keep sente. The sequence played lft white in gote, and enabled black to take the initiative in the centre with 117.]
;B[bf]
;W[jj]
;B[kj]
;W[bh]
;B[rg]
;W[qh]
;B[ij]
;W[ji]
;B[ik]
;W[ki]
;B[kb]
;W[ok]
;B[nl]
;W[dg]
;B[df]
;W[ch]
;B[cf]
;W[af]
;B[ae]
;W[ag]
;B[bb]C[117-131: Both players have been striving to gain on the centre-left. The sitution is now fairly conclusive in this area and attention turns to the right, where white tries to take advantage of the weakness at 138.]
;W[lj]
;B[kk]
;W[lk]
;B[ll]
;W[kc]
;B[jb]
;W[lg]C[This move hits the vital point of black's formation.]
;B[lf]
;W[nh]C[White cannot play directly at 149 because there are too many cutting points.]
;B[mi]
;W[gb]C[Black should make eyes for his group by playing 141 and 143.]
;B[mg]
;W[li]
;B[oi]LB[mj:B][nj:A][oj:C][ml:D]C[Another mistake. If black answers 146 at 152, then after the sequence: W 'A', B 'B' , W151, B 'C', W147, B 'A', W 'D', black cannot hold on to his territory.]
;W[mh]
;B[oh]
;W[og]
;B[ng]
;W[lh]
;B[mk]
;W[pi]
;B[ii]
;W[ih]
;B[lb]
;W[mb]
;B[qg]
;W[pg]
;B[ga]
;W[fa]
;B[ha]
;W[nr]C[Black has survived, but he has lost a lot of potential territory. With this move white is ahead.]
;B[gk]
;W[hl]
;B[gl]
;W[hj]
;B[hi]
;W[gj]
;B[fk]
;W[gi]
;B[hh]
;W[gh]
;B[hg]
;W[hf]
;B[kg]
;W[jh]
;B[ek]
;W[dk]
;B[ei]
;W[gg]
;B[im]
;W[nq]
;B[np]
;W[ol]
;B[om]
;W[eh]
;B[fi]
;W[os]C[It is better to play at 189.]
;B[bk]
;W[bj]
;B[bm]
;W[ak]C[White must play rather delicately here, as his groups on the left and upper sides are only just alive, and black may be able to save 101 in sente.]
;B[al]
;W[bl]
;B[dp]
;W[dq]
;B[bk]
;W[oe]
;B[ne]
;W[bl]
;B[ed]
;W[am]
;B[ec]
;W[fh]
;B[an]
;W[al]
;B[mq]
;W[mr]
;B[pr]
;W[il]
;B[jl]
;W[jm]
;B[kl]
;W[jo]
;B[jn]
;W[mj]
;B[nj]
;W[rh]
;B[rf]
;W[ge]
;B[kp]
;W[jq]
;B[eo]
;W[dm]
;B[dn]
;W[eq]
;B[ma]
;W[na]
;B[la]
;W[pa]
;B[or]
;W[ee]
;B[de]
;W[pf]
;B[da]
;W[gc]
;B[ps]
;W[ns]
;B[ap]
;W[aq]
;B[sd]
;W[sc]
;B[sh]
;W[si]
;B[sf]
;W[ao]
;B[bn]
;W[eg]
;B[di]
;W[ff]
;B[ke]
;W[jg]
;B[se]
;W[ap]
;B[sg])